# -*- mode: TCL; fill-column: 75; tab-width: 8; coding: iso-latin-1-unix -*-

#

#	$Id: Variable.tcl,v 1.4 2001/12/09 05:04:02 idiscovery Exp $

#

# Variable.tcl --

#

#	Routines in this file are used to set up and operate variables

#	for classes that support the -variable option

#

# Copyright (c) 1993-1999 Ioi Kim Lam.

# Copyright (c) 2000-2001 Tix Project Group.

#

# See the file "license.terms" for information on usage and redistribution

# of this file, and for a DISCLAIMER OF ALL WARRANTIES.

#

# tixVariable:ConfigVariable --

#

# 	Set up the -variable option for the object $w

#

# Side effects:

#

#	data(-variable) is changed to the name of the global variable

#	if the global variable exists, data(-value) takes the value of this

#	variable.

#	if the global variable does not exist, it is created with the

#	current data(-value)

#

# Return value:

#

#	true is data(-value) is changed, indicating that data(-command)

#	should be invoked.

#

proc tixVariable:ConfigVariable {w arg} {

    upvar #0 $w data

    set changed 0

    if {$data(-variable) != ""} {

	uplevel #0 \

	    [list trace vdelete $data(-variable) w "tixVariable:TraceProc $w"]

    }

    if {$arg != ""} {

	if {[uplevel #0 info exists [list $arg]]} {

	    # This global variable exists, we use its value

	    #

	    set data(-value) [uplevel #0 set [list $arg]]

	    set changed 1

	} else {

	    # This global variable does not exist; let's set it 

	    #

	    uplevel #0 [list set $arg $data(-value)]

	}

	uplevel #0 \

	    [list trace variable $arg w "tixVariable:TraceProc $w"]

    }

    return $changed

}

proc tixVariable:UpdateVariable {w} {

    upvar #0 $w data

    if {$data(-variable) != ""} {

	uplevel #0 \

	    [list trace vdelete  $data(-variable) w "tixVariable:TraceProc $w"]

	uplevel #0 \

	    [list set $data(-variable) $data(-value)]

	uplevel #0 \

	    [list trace variable $data(-variable) w "tixVariable:TraceProc $w"]

	# just in case someone has another trace and restricted my change

	#

	set data(-value) [uplevel #0 set [list $data(-variable)]]

    }

}

proc tixVariable:TraceProc {w name1 name2 op} {

    upvar #0 $w data

    set varname $data(-variable)

    if {[catch {$w config -value [uplevel #0 [list set $varname]]} err]} {

	uplevel #0 [list set $varname [list [$w cget -value]]]

	error $err

    }

    return

}

proc tixVariable:DeleteVariable {w} {

    upvar #0 $w data

    # Must delete the trace command of the -variable

    #

    if {$data(-variable) != ""} {

	uplevel #0 \

	    [list trace vdelete $data(-variable) w "tixVariable:TraceProc $w"]

    }

}